The present invention generally relates to promoters and methods of use and fabrication thereof, and particularly to a promoter used to express a gene, a vector including a promoter, a method of producing a target protein, a method of producing a transformed cell and/or a plant, a transformed plant, a transformed seed, a transformed cell, and PCR primers for a promoter.
A promoter may relate to a genomic region located upstream of a structural gene and may function in the transcription of a structural gene, for example, into mRNA. A promoter may be activated by binding of general transcription factors, and may include base sequences such as a TATA box and/or CAT box which may assist to regulate gene expression. For example, promoters linked to genes may be constitutively activated by general transcription factors to express genes associated with proteins needed for the basal metabolism of a living organism and which may be required in cells at a given concentration. Promoters may also be activated when proteins are needed which are not ordinarily present or only required under special circumstances. For example, inducible promoters may be activated by binding of specific transcription factors, which may be activated in an organism's developmental processes or by external stimuli resulting from surrounding environmental factors.
A foreign gene (i.e., transgene) introduced into a plant, forming a plant having novel characteristics which may develop an agricultural field, may be influenced by transcriptional, post-transcriptional, translational and post-translational elements. A promoter may belong to a transcriptional element and may directly influence transcription of a transgene, for example, to change the expression level of a transgene. A promoter may be the most important factor to change the expression stage or the tissue and/or cell specificity of a transgene.
Although promoters have been isolated from plants to express a transgene, only a few promoters may be practical for use in the transformation of plants. For example, a CaMV (cauliflower mosaic virus) 35S promoter and its derivatives may induce expression of genes in plant tissues and exhibit high activity, for example in vascular tissues and root/leave cells. However, a CaMV 35S promoter has relatively less activity in monocot plants, such as a rice plant, and does not exhibit any activity in certain cells, such as pollen.
Promoters from dicot plants which have been investigated for the transformation of monocot plants have exhibited relatively lower activity compared to promoters originating from monocot plants. A rbcS (ribulose bisphosphate carboxylase/oxygenase small subunit) promoter of rice, a Act1 (actin1) promoter of rice, and a Ubi1 promoter of maize are examples of promoters from monocot plants which have been investigated in the transformation of monocot plants. While Act1 and Ubi1 promoters exhibit a relatively high activity in monocot plants compared to a CaMV 35S promoter, there are drawbacks. For example, the Act1 promoter exhibits activity mainly in vegetative tissue and reproductive tissue, and thus is not effective for expression of a ubiquitous gene in monocot plants. Although the Ubi1 promoter exhibits activity in numerous types of cells, it does not exhibit activity in the substantially all tissues of a plant. Also, while the Ubi1 promoter exhibits a strong activity, especially in young roots, the activity is greatly reduced over time, for example as the root grows.
Accordingly, there is a need for developing a promoter exhibiting a strong, stable and ubiquitous activity in the transformation of plants, including monocot plants. There is a need for suitable promoters useful in the substantially uniform expression of a gene in substantially all the tissues of a plant. There is a need for suitable promoters useful in the production of transformed compositions, and suitable methods for fabricating the same. There is also a need for suitable primers for a variety of novel promoters.